Usb charger, mobile terminal and charging method thereof

ABSTRACT

A USB charger, a mobile terminal, and a charging method are provided. The USB charger for charging a mobile terminal, includes a first logic control unit through which bidirectional communication is established between the USB charger and the mobile terminal, wherein the first logic control unit is configured to: send, to the mobile terminal, a first signal which includes a maximum output capability of the USB charger; receive, from the mobile terminal, a second signal which indicates magnitude of a voltage requested by the mobile terminal; and adjust a voltage output from the USB charger to be consistent with the voltage requested by the mobile terminal. Accordingly, the USB charger and the mobile terminal can communicate with each other through a single signal wire. Thus, the voltage output from the USB charger can be intelligently controlled, so as to charge the mobile terminal in a fast, safe, and simply way.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to Chinesepatent application No. 201410438522.X, filed on Aug. 29, 2014, theentire disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to mobile communication, andmore particularly, to a USB charger, a mobile terminal, and chargingmethods thereof.

BACKGROUND

Step-down switching power supply circuits typically have an outputvoltage lower than an input voltage, an output current greater than aninput current, and thus an output power slightly less than an inputpower. Therefore, the switching power supply circuit has relatively highefficiency and low heat dissipation. Further, if the output voltage isnot much different from the input voltage, the difference between theoutput current and the input current won't be great, either.

Referring to FIG. 1, a circuit of an existing standard USB charger isillustrated. The USB charger includes four pins which are respectivelyconnected with a data signal wire D+, a data signal wire D−, a powerwire VBUS and a ground wire GND. The USB charger is able to convert analternating current (AC) in high voltage level into a direct current(DC) in low voltage level. The USB charger further includes a feedbackcircuit to control a voltage of the DC output from the USB charger. Asthe USB charger is a standard charger, the data signal wire D+ and thedata signal wire D− are short connected, which is stipulated in USBcharger protocol. Therefore, the type of the USB charger (e.g. astandard USB charger, or a non-standard USB charger such as a USBinterface of a computer) is able to be determined by detecting if thedata signal wire D+ and the data signal wire D− are short connected. TheUSB charger in the present disclosure refers to a USB charger includingfour pins as recited above. And the USB charger may further include anID pin.

When taking the USB charger and a battery required to be charged as acharging circuit, an input voltage of the charging circuit refers to thevoltage output from the charger, which is normally 5V, and an outputvoltage of the charging circuit refers to the voltage input to thebattery, which is normally from 3.6V to 4.2V. Thus, a current chargedinto the battery (hereinafter referred to as an output current of thecharging circuit) is slightly greater than a current provided by thecharger (hereinafter referred to as an input current of the chargingcircuit).

When the battery is desired to be charged with a greater current toincrease charging efficiency, the output current of the charging circuitis required to be increased. Accordingly, the input current of thecharging circuit should be increased. As a result, voltage drop will beincreased due to the impedances of USB signal wires and the greaterinput current, thus leading to a decrease in circuit output efficiency.Accordingly, in existing techniques, bulk charging is hard to beachieved, and the maximum input current is normally limited to 1.5 A.

SUMMARY

According to one embodiment of the present disclosure, a USB chargeradapted to charge a mobile terminal is provided. The USB chargerincludes a first logic control unit through which bidirectionalcommunication is established between the USB charger and the mobileterminal, wherein the first logic control unit is configured to: send,to the mobile terminal, a first signal which indicates a maximum outputcapability of the USB charger; receive, from the mobile terminal, asecond signal which indicates magnitude of a voltage requested by themobile terminal; and adjust a voltage output from the USB charger to beconsistent with the voltage requested by the mobile terminal.

In some embodiments, the voltage requested by the mobile terminal isdetermined based on the maximum output capability of the USB charger anda maximum load capability of the mobile terminal. In some embodiments,the maximum output capability of the USB charger represents maximummagnitudes of voltage and current output from the USB charger.

In some embodiments, the bidirectional communication is establishedthrough one signal wire of an interface of the USB charger.

In some embodiments, the signal wire includes a data signal wire D+, adata signal wire D−, or an ID signal wire.

In some embodiments, the first signal and the second signal are pulsesignals. As such, the bidirectional communication between the USBcharger and the mobile terminal is achieved by way of pulse signals.

In some embodiments, the first logic control unit includes: a firstlogic control circuit, a first switch transistor and a first comparator,wherein the first logic control circuit is configured to: send the firstsignal to the mobile terminal through the first switch transistor, andreceive and parse the second signal from the mobile terminal through thefirst comparator.

According to one embodiment of the present disclosure, a mobile terminaladapted to be charged by the USB charger recited above is provided. Themobile terminal includes a second logic control unit through whichbidirectional communication is established between the USB charger andthe mobile terminal, wherein the second logic control unit is configuredto: receive, from the USB charger, a first signal which includes amaximum output capability of the USB charger; send, to the USB charger,a second signal which indicates magnitude of a voltage requested by themobile terminal; and adjust a charging setting, when a voltage outputfrom the USB charger is consistent with the voltage requested by themobile terminal. The charging setting of the mobile terminal may includemagnitudes of a charging current and a charging temperature that themobile terminal can handle. In some embodiments, the magnitude of thecharging temperature that the mobile terminal can handle is controlledby adjusting a threshold value of overheat protection of the mobileterminal. Therefore, the mobile terminal is suitable to be charged withmore current through adjusting the charging setting correspondingly.

In some embodiments, the voltage requested by the mobile terminal isdetermined based on the maximum output capability of the USB charger anda maximum load capability of the mobile terminal.

In some embodiments, the bidirectional communication is establishedthrough one signal wire of a USB interface of the mobile terminal.

In some embodiments, the one signal wire includes a data signal wire D+,a data signal wire D−, or an ID signal wire.

In some embodiments, the first signal and the second signal are pulsesignals.

In some embodiments, the second logic control unit includes: a secondlogic control circuit; a second switch transistor; a second comparator;and wherein the second logic control circuit is configured to: send thesecond signal to the USB charger through the second switch transistor,and receive the first signal from the USB charger thorough the secondcomparator.

According to one embodiment of the present disclosure, a method ofcharging a mobile terminal as recited above is provided. The methodincludes: sending a handshake request signal to a USB charger;receiving, from the USB charger, a first signal which includes a maximumoutput capability of the USB charger; sending, to the USB charger, asecond signal which indicates magnitude of a voltage requested by themobile terminal; and adjusting a charging setting of the mobile terminalwhen a voltage output from the USB charger is consistent with thevoltage requested by the mobile terminal.

In some embodiments, the method further includes detecting a type of theUSB charger.

In some embodiments, the method further includes: detecting a chargingstate of the mobile terminal; and reducing a charging current when thecharging state is detected abnormal. As such, the mobile terminal isable to be charged in a safe way.

In some embodiments, the handshake request signal, the first signal andthe second signal are pulse signals.

In some embodiments, the method further includes: charging the mobileterminal with a regular voltage, when the first signal is not receivedfrom the USB charger. In some embodiments, when the mobile terminal orthe USB charger is not configured to be that as provided by the presentdisclosure, the first signal may unable to be received from the USBcharger, in this case, the mobile terminal can be charged in a regularway.

According to one embodiment of the present disclosure, a method ofcharging a mobile terminal by a USB charger as recited above isprovided. The method includes: receiving a handshake request signal fromthe mobile terminal; sending, to the mobile terminal, a first signalwhich includes a maximum output capability of the USB charger;receiving, from the mobile terminal, a second signal which indicatesmagnitude of a voltage requested by the mobile terminal; and adjusting avoltage output from the USB charger to be consistent with the voltagerequested by the mobile terminal.

In some embodiments, the method further includes: charging the mobileterminal with a regular voltage, when the handshake request signalreceived is unable to be parsed by the USB charger.

In some embodiments, the method further includes: charging the mobileterminal with a regular voltage, when the USB charger is disconnectedwith the mobile terminal.

In some embodiments, the first signal and the second signal are pulsesignals.

Accordingly, the USB charger and the mobile terminal provided by thepresent disclosure are able to communicate with each other through asingle signal wire. Thus, a bidirectional communication between the USBcharger and the mobile terminal is established, wherein thebidirectional communication is achieved by way of pulse signals.Accordingly, the voltage output from the USB charger is able to beintelligently controlled, and the mobile terminal is able to be chargedin a fast, safe, and simply way. Furthermore, when the mobile terminalis not configured to be the mobile terminal as provided by the presentdisclosure, or the USB charger is not configured to be the USB chargeras provided by the present disclosure, the mobile terminal will becharged in a regular way. Thus, the charging method provided by thepresent disclosure has good compatibility.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a circuit of an existing standard USBcharger;

FIG. 2 schematically illustrates a diagram of a USB charger according toone embodiment of the present disclosure;

FIG. 3 schematically illustrates a diagram of a USB interface of amobile terminal according to one embodiment of the present disclosure;

FIG. 4 schematically illustrates a circuit of a USB charger according toone embodiment of the present disclosure;

FIG. 5 schematically illustrates a circuit of a USB interface of amobile terminal according to one embodiment of the present disclosure;

FIG. 6 schematically illustrates a flow chart of a method of charging amobile terminal by a USB charger; and

FIG. 7 schematically illustrates a flow chart of a method of charging amobile terminal by a USB charger.

DETAILED DESCRIPTION

In order to clarify the objects, characteristics and advantages of thepresent disclosure, embodiments of the present disclosure will bedescribed in detail in conjunction with the accompanying drawings. Thedisclosure will be described with reference to certain embodiments.Accordingly, the present disclosure is not limited to the embodimentsdisclosed. It will be understood by those skilled in the art thatvarious changes may be made without departing from the spirit or scopeof the disclosure.

As recited in the background, voltage drop caused by impedances of USBwires is a significant hinder of charging a mobile terminal in a largecurrent. Therefore, the present disclosure provides a USB charger whichis able to communicate with a mobile terminal by way of bidirectionalcommunication, thus a voltage output from the charger is under control.Accordingly, the voltage output from the charger is able to be enlarged,and when the voltage output from the charger (referred to as an inputvoltage) is far greater than a voltage of a battery required to becharged (referred to as an output voltage), a larger charging current(referred to as an output current) is able to be obtained withoutenlarging a current of the charger (referred to as an input current),wherein the output current is able to be used to charge the mobileterminal. Since the output current is small, effects of the voltage dropis not significant.

In the present disclosure, the USB charger and the mobile terminal areboth configured with a logic control unit for bidirectionalcommunication therebetween. Thus, a maximum output capability of thecharger can be acquired by the mobile terminal, while a maximum loadcapability of the mobile terminal can be acquired by the charger. Itshould be noted that, in some embodiments, the maximum output capabilityof the charger represents maximum magnitudes of voltage and currentoutput from the USB charger, and the maximum load capability of themobile terminal represents maximum magnitudes of voltage and currentoutput that the mobile terminal can bear. Accordingly, the mobileterminal is able to be charged in a fast, and safety way.

According to a USB charger provided by one embodiment of the presentdisclosure, a first logic control unit is configured to establish abidirectional communication between the USB charger and a mobileterminal. Specifically, the first logic control unit is adapted to:send, to the mobile terminal, a first signal which includes a maximumoutput capability of the USB charger; receive, from the mobile terminal,a second signal which indicates magnitude of a voltage requested by themobile terminal; and adjust a voltage output from the USB charger to beconsistent with the voltage requested by the mobile terminal. Therefore,the mobile terminal is able to be charged in a fast and safe way.

The voltage requested by the mobile terminal is determined based on themaximum output capability of the USB charger and the maximum loadcapability of the mobile terminal. In some embodiments, the voltagerequested by the mobile terminal is the smaller one of the maximumvoltage can be provided by the USB charger and the maximum voltage thatthe mobile terminal can bear. It should be noted that, the maximum loadcapability of the mobile terminal is determined by correspondinghardware thereof.

Furthermore, the first logic control unit is coupled with one singlesignal wire of an interface of the USB charger. In other word, the USBcharger and the mobile terminal communicate with each other through onesingle signal wire of the USB charger by way of a bidirectionalcommunication. In some embodiments, the bidirectional communication isachieved through pulse signals. Specifically, the first logic controlunit is adapted to receive and send pulse signals, and adjust a feedbackcontrol circuit of the USB charger to control the voltage output fromthe USB charger (refers to the input voltage of the charging circuit).

Referring to FIG. 2, a diagram of a USB charger according to oneembodiment of the present disclosure is illustrated. The USB chargerincludes a first logic control unit which is coupled with a data signalwire D+ of the USB charger. Further, the USB charger is a standardcharger, thus the data signal wire D+ is connected with a data signalwire D− of the USB charger. It should be noted that, in someembodiments, the first logic control unit may be coupled with the datasignal wire D−. In some embodiments, the USB charger may include an IDpin (not shown in FIG. 2), in this case, the first logic control unitmay be coupled with any one of signal wires of the ID pin. In someembodiments, the USB charger may be a non-standard USB charger, in thiscase, an additional signal wire may be configured for being coupled withthe first logic control unit. Accordingly, the signal wire coupled withthe first logic control unit may be any other suitable wires besides thedata signal wire D+, as long as the bidirectional communication betweenthe USB charger and the mobile terminal can be obtained.

The USB charger is able to be employed to charge a mobile terminal.Accordingly, a charging method is provided by the present disclosure.Specifically, the mobile terminal firstly determines a type of the USBcharger, wherein when the data signal wire D+ is connected with the datasignal wire D−, the USB charger is determined as a standard USB charger;secondly, the mobile terminal disconnects the data signal wire D−, andsends a pulse signal to the USB charger through the data signal wire D+,wherein the pulse signal is decoded by the first logic control unit ofthe USB charger to obtain a first value; thirdly, the mobile terminalreceives and decodes the first value so as to pair the mobile terminaland the USB charger; fourthly, the mobile terminal sends a voltage tothe USB charger, wherein the USB charger changes the voltage outputbased on the voltage requested by the mobile terminal; and finally, themobile terminal adjusts a charging setting thereof when the voltageoutput from the USB charger changes. It should be noted that, thecharging setting of the mobile terminal may include magnitudes of acharging current and a charging temperature that the mobile terminal canhandle. Through adjusting the charging setting, the mobile terminal issuitable to be charged with more current. Accordingly, bulk charge canbe achieved by enlarging the voltage output from the USB charger.

Correspondingly, a mobile terminal adapted to be charged by the USBcharger as illustrated above is also provided by the present disclosure.The mobile terminal includes a second logic control unit which isadapted to parse signals from the USB charger for establishing abidirectional communication with the USB charger. The second logiccontrol unit is configured to: receive a maximum output capability ofthe USB charger; send a voltage requested by the mobile terminal to theUSB charger, wherein the voltage requested by the mobile terminal isdetermined based on the maximum output capability of the USB charger;and adjust a charge setting of the mobile terminal when a voltage outputfrom the USB charger changes, such that a bulk charge of the mobileterminal is achieved. It should be noted that, the charging setting ofthe mobile terminal may include magnitudes of charging current andcharging temperature that the mobile terminal can handle. Throughadjusting the charging setting, the mobile terminal is suitable to becharged with more current.

Specifically, the mobile terminal includes a USB interface correspondingto the interface of the USB charger. The second logic control unit iscoupled with only one signal wire of the USB interface of the mobileterminal. In other words, the second logic control unit communicateswith the USB charger through only one signal wire of the USB interfaceof the mobile terminal. Furthermore, the second logic control unit isadapted to receive and send pulse signals.

Referring to FIG. 3, a diagram of the USB interface of the mobileterminal is illustrated. As shown, the second logic control unit is onlycoupled with a data signal wire D+ of the USB interface of the mobileterminal. Further, the data signal wire D+ and a data signal wire D− ofthe USB interface of the mobile terminal are coupled with a USB PHYmodule, wherein the USB PHY module is a common hardware structure moduleunder regulation of the USB protocol. It should be noted that, in someembodiments, the second logic control unit may be coupled with the datasignal wire D−. In some embodiments, the mobile terminal may include anID pin (not shown in FIG. 3), in this case, the second logic controlunit may be coupled with any one of signal wires of the ID pin. In someembodiments, the USB interface of the mobile terminal may be anon-standard USB interface, and an additional signal wire may beconfigured for coupling with the second logic control unit. Accordingly,the signal wire coupled with the second logic control unit may be anyother suitable wires besides the data signal wire D+, as long as thebidirectional communication between the USB charger and the mobileterminal can be achieved.

In some embodiments, the mobile terminal is configured to: disconnectwith the USB PHY module when a standard USB charger is detected beingcoupled with the mobile terminal; and connect with the second logiccontrol unit for implementing a charging operation. As shown in FIG. 3,switches S2 and S3 are switched off, and a switch S1 is switched on,thus the second logic control unit is able to communicate with the USBcharger through the data signal wire D+.

Referring to FIG. 4, a circuit structure of a USB charger according toone embodiment of the present disclosure is illustrated. Referring toFIG. 5, a circuit structure of a USB interface of a mobile terminalaccording to one embodiment of the present disclosure is illustrated. Asshown in FIG. 4 and FIG. 5, the bidirectional communication between theUSB charger and the mobile terminal includes an OD (Open Drain), apull-up resistor, and a pulsed high level of 3.3 V, wherein the pull-upresistor is configured in the mobile terminal.

Referring to FIG. 4, the first logic control unit (indicated by dashedline box in FIG. 4) includes: a first logic control circuit 401, a firstswitch transistor N1, and a first comparator U1. The first logic controlunit is coupled with the data signal wire D+ of the USB charger, and thedata signal wire D+ and the data signal wire D− are coupled together.

Specifically, a gate of the first switch transistor N1 is coupled withthe first logic control circuit 401, a source of the first switchtransistor N1 is grounded, and a drain of the first logic controlcircuit is coupled with the data signal wire D+. The first comparator U1has a first input terminal coupled with the data signal wire D+, anoutput terminal coupled with the first logic control circuit 401, and asecond input terminal coupled with a voltage of 2V. The first logiccontrol circuit 401 is configured to: send a first signal (e.g. a pulsesignal) to the mobile terminal through the first switch transistor N1;and receive and parse a second signal (e.g. a pulse signal) though thefirst comparator U1. In some embodiments, the first signal may be usedto inform the maximum output capability of the USB charger, the secondsignal may be used to indicate the voltage requested by the mobileterminal.

The USB charger further includes a secondary control circuit adapted toconvert alternating current with a high level into direct current with alow level such as 5V. The secondary control circuit can be implementedthrough ways known to person in the art, which will not be illustratedin detail herein.

Referring to FIG. 5, the second logic control unit (indicated by dashedline box) includes: a second logic control circuit 501, a second switchtransistor N2, and a second comparator U2. The second logic control unitis coupled with the data signal wire D+ of the USB interface of themobile terminal.

Specifically, a gate of the second switch transistor N2 is coupled withthe second logic control circuit 501, a source of the second switchtransistor N2 is grounded, and a drain of the second logic controlcircuit is coupled with the data signal wire D+ and a pull-up resistorR1. The second comparator U2 has a first input terminal coupled with thedata signal wire D+, an output terminal coupled with the second logiccontrol circuit 501, and a second input terminal coupled with a voltageof 2V. The second logic control circuit 501 is configured to: send thesecond signal to the USB charger through the second switch transistorN2; and receive the first signal from the USB charger.

As shown in FIG. 5, the mobile terminal further includes a BC1.2 modulewhich is adapted to determine a type of a charger coupled with themobile terminal, wherein the BC1.2 module is a common hardware structuremodule under regulation of the USB protocol. Switches S6 and S7 of themobile terminal are switched on, and switches S4, S5 and S8 of themobile terminal are switched off by default. When a standard USB chargeris detected by the BC1.2 module being coupled with the mobile terminal,the switches S6, S7 will be switched off, and the switch of S8 will beswitched on. Since then, the mobile terminal is able to send a pulsesignal through the data signal wire D+, so as to establish bidirectionalcommunication with the USB charger.

Referring to FIG. 4 and FIG. 5, the pull-up resistor of the data signalwire D+ is configured on the mobile terminal, thus a high level of 3.3Vwill always exist on the data signal wire D+ as long as the USB chargerand the mobile terminal are coupled together. Therefore, when thevoltage output from the USB charger is detected being in a low level fora preset time period, such as 1 second, the charger will be determinedas being disconnected with the mobile terminal, wherein the voltageoutput from the USB charger is detected by the first comparator U1. Inthis case, for the safety usage of the USB charger, the voltage outputfrom the USB charger should be controlled to back to 5V immediately, anda capacitor discharger circuit should be enabled to reduce the voltageoutput from the USB charger at once. It should be noted that, even whenthe USB charger and the mobile terminal are in normal communication,there is a temporary low level on the signal wire D+ for a very shorttime period, which should be ignored. In other words, during this veryshort time period, the voltage output from the USB charger should not bechanged to 5V. In some embodiments, this temporary low level can beavoided by vibration reduction technologies known to person in the art.

Referring to FIG. 6, a method of charging a mobile terminal isillustrated. The method which is illustrated from the aspect of themobile terminal includes follow steps from step S601 to S616.

In step S603, sending a handshake request signal to a USB charger. Insome embodiments, the handshake request signal is a pulse signal.

In step S605, receiving a first signal from the USB charger, wherein thefirst signal is used to inform the mobile terminal a maximum outputcapability of the USB charger.

In step S607, sending a second signal to the USB charger based on thefirst signal received, wherein the second signal is used to indicate theUSB charger a voltage requested by the mobile terminal.

In step S609, when a voltage output from the USB charger is consistentwith the voltage requested by the mobile terminal, adjusting a chargingsetting of the mobile terminal.

In some embodiments, the method may further include a step S601 beforethe mobile terminal sends the handshake request signal to the USBcharger (S603). In step S601, detecting a type of the USB chargercoupled with the mobile terminal, wherein when the USB charger isdetected as a standard USB charger (S6011), S603 to S609 will beimplemented.

In some embodiments, the method may further include a step S608 afterthe mobile terminal sends, to the USB charger, a voltage requested bythe mobile terminal (S607). In step S608, detecting if the voltageoutput from the USB charger is inconsistent with the voltage requestedby the mobile terminal (S608).

In some embodiments, if the USB charger is detected as a non-standardUSB charger (S6012), then S611 will be implemented to charge the mobileterminal with a regular voltage. In some embodiments, the regularvoltage may be 5V.

In some embodiments, in step S603, if receives no response from the USBcharger (S6031), when the mobile terminal sends the handshake requestsignal to the USB charger, then S611 will be implemented to charge themobile terminal with the regular voltage, such as 5V. It should be notedthat, no response is received may be under the following twocircumstances: first, the USB charger does not include the first logiccontrol unit and is unable to communicate with the mobile terminal bybidirectional communication, in other words, the USB charger is aregular charger; second, the USB charger is unable to parse thehandshake request signal from the mobile terminal, such as because ofmalfunction of the USB charger. Under the above two circumstances,bidirectional communication between the USB charger and the mobileterminal is unable to be established, thus no response is received fromthe USB charger. Accordingly, even when the USB charger coupled with themobile terminal does not include the first logic control unit, themobile terminal is able to be charged with regular voltage. Therefore,the mobile terminal provided by the present disclosure has a strongself-adaptability.

In some embodiments, in step S608, when the voltage output from the USBcharger is inconsistent with the voltage requested by the mobileterminal (S610), step S611 will be implemented to charge the mobileterminal with the regular voltage, such as 5V.

Accordingly, in the method of charging recited above, the USB chargerand the mobile terminal are able to communicate with each other by wayof the bidirectional communication. Thus, the mobile terminal is able toacquire the maximum output capability of the USB charger. Therefore, thevoltage output from the USB charger is able to be enlarged, so as tocharge the mobile terminal by way of bulk charging.

In some embodiments, the method may further include follow steps for thesafety of the charging operation.

In step S613, detecting a charging state of the mobile terminal, whereinthe charging state includes at least one selected from a groupconsisting of a charging voltage, a charging current and a temperature.

In step S615, reducing a charging current, when the charging state isdetected abnormal.

For example, when the temperature of the mobile terminal is extremelyhigh (S614), the charging current is reduced to avoid an unsafesituation may be caused by overheat of the mobile terminal. Further,when the charging state is detected normal, the charging setting of themobile terminal will remain unchanged (S616).

Accordingly, the method provided by the present disclosure as recitedabove is able to charge the mobile terminal in a fast (as bulk chargingis able to be achieved) and safe way.

Referring to FIG. 7, a method of charging a mobile terminal according toone embodiment of the present disclosure is illustrated. The methodwhich is illustrated from the aspect of the USB charger includesfollowing steps from step S701 to S709.

In step S701, receiving a handshake request signal from the mobileterminal. In some embodiments, the handshake request signal is a pulsesignal.

In step S703, sending a first signal to the mobile terminal, wherein thefirst signal is used to inform the mobile terminal a maximum outputcapability of the USB charger.

In step S705, receiving a second signal from the mobile terminal,wherein the second signal is used to indicate the USB charger a voltagerequested by the mobile terminal.

In step S707, controlling a voltage output from the USB charger to beconsistent with the voltage requested by the mobile terminal.

In some embodiments, in step S701, if the USB charger is able to parsethe handshake request signal correctly (S702), then S703 will beimplemented; and if the USB charger is unable to parse the handshakerequest signal correctly (S704), then S709 will be implemented to chargethe mobile terminal with the regular voltage, such as 5V.

In some embodiments, the method may further include: if the USB chargeris disconnected with the mobile terminal (S708), charging the mobileterminal under the regular charging voltage, such as 5V. It should benoted that, before the handshake request signal is received, the USBcharger may charge the mobile terminal under the regular chargingvoltage by default.

In some embodiment, in S704, if the USB charger is unable to parse thehandshake request signal correctly, the following two circumstances mayexist. First circumstance is, the mobile terminal does not include thesecond logic control unit and is unable to communicate with the USBcharger by way of bidirectional communication, in other words, themobile terminal is a regular mobile terminal. Second circumstance is,the handshake request signal from the mobile terminal is unable to beparsed by the USB charger. Under the above two circumstances,bidirectional communication between the USB charger and the mobileterminal is unable to be established. Accordingly, even the mobileterminal coupled with the USB charger does not include the second logiccontrol unit, the USB charger is able to charge the mobile terminal withthe regular charging voltage. Therefore, the USB charger provided by thepresent disclosure has a strong self-adaptability.

In some embodiments, the bidirectional communication between the USBcharger and the mobile terminal is established by way of pulse signal.It should be noted that, the way of bidirectional communication is notlimited to the pulse signal, any other suitable way, such as fiber-opticcommunication, may be employed.

In some embodiments, encoding of the pulse signal may be achieved by wayof A+B+C, wherein A represents an identification code with 6 bits, Brepresents an instruction code with 9 bits (the former 6 bits representsvoltage value, and the later 3 bits represents current value), and Crepresents a parity bit with 1 bit.

In some embodiments of the present disclosure, the identification codeis able to be defined as 011011. Thus, only a pulse started with thisidentification code is taken as valid. Further, an even parity isemployed herein. A request pulse is able to be defined as011011+111000111+0.

Table 1 illustrates how to encode pulse signals of different voltagesand currents according to one embodiment of the present disclosure.

TABLE 1 reserved voltage voltage current 3.7 V 000000  5 V 001001 1 A000 3.9 V 000001  9 V 001011 2 A 001 4.1 V 000010 12 V 001101 3 A 0104.3 V 000011 20 V 001111 4 A 011 4.5 V 000100 4.7 V 000101 5.0 V 001001

It should be noted that, the Table 1 is only an example for illustratinghow to encode pulse signals of different voltages and currents. Inpractice, some modifications may be made to the Table 1 is required.

According to the Table 1, the bulk charging between a mobile terminaland a USB charger is able to be implemented as following. It should benoted that, a maximum output voltage and a maximum output current of theUSB charger are given. For example, the maximum voltage output from theUSB charger is 12V, and the maximum current output from the USB chargeris 2 A. Thus, the pulse is able to be defined as 001101+001 according toTable 1.

First, the mobile terminal sends a handshake request signal to the USBcharger, wherein the handshake request signal is a require pulse definedas 011011+111000111+0.

When receives the require pulse defined as 011011+111000111+0, the USBcharger will send 011011+001101001+0 to the mobile terminal to informthe mobile terminal that the maximum output voltage and current of theUSB charger are respectively 12V and 2 A (that is, the maximum outputcapability of the USB charger).

When receives the maximum output capability of the USB charger (12V and2 A), the mobile terminal will send, to the USB charger, a voltagerequested by the mobile terminal. The voltage requested by the mobileterminal is able to be defined according to the Table 1. For example, ifthe mobile terminal sends 011011+001011+1 to the USB charger, itrepresents that the voltage requested by the mobile terminal is 9V. Insome embodiments, the voltage requested by the mobile terminal isdetermined by the maximum output capability of the USB charger and thehardware of the mobile terminal (e.g. charging voltage and chargingcurrent that the mobile terminal can handle).

Then, a voltage output from the USB charger will be adjusted by the USBcharger based on the voltage requested by the mobile terminal. Such as,the voltage output from the USB charger can be adjusted to be consistentwith the voltage requested by the mobile terminal.

When the voltage output from the USB charger is detected being changed,the mobile terminal will adjust a charging setting thereof, such thatthe bulk charging is able to be achieved. The charging setting of themobile terminal may include magnitudes of a charging current and acharging temperature that the mobile terminal can handle. Throughadjusting the charging setting, the mobile terminal is suitable to becharged with more current.

Usually, the magnitude of the charging current that the mobile terminalcan handle may be determined according to the smaller one of: a firstpre-set bulk charging current, wherein the first pre-set bulk chargingcurrent is determined based on corresponding hardware (e.g. a battery,PCB Trace) of the mobile terminal, in other words, the first pre-setbulk charging current is the maximum current that the mobile terminalcan handle; and a second pre-set bulk charging current, wherein thesecond pre-set bulk charging current is determined based on:I_(chg)=(P*η)/Z, wherein I_(chg) represents the second pre-set bulkcharging current, P represents an output power of the USB charger, ηrepresents a conversion efficiency, and Z represents a full chargedvoltage of the mobile terminal. In some embodiments, the full chargedvoltage of the mobile terminal may be 4.2V or 4.35V.

For example, supposing a DCDC loss is 20%, a line loss is 10%, the fullcharged voltage of the mobile terminal is 4.2V, thus the second pre-setbulk charging current I_(chg)=(P*70%)/4.2V.

Accordingly, the USB charger and the mobile terminal provided by thepresent disclosure are able to communicate with each other through asingle signal wire. Thus, a bidirectional communication between the USBcharger and the mobile terminal is established, wherein thebidirectional communication is achieved by way of pulse signals.Accordingly, the voltage output from the USB charger is able to beintelligently controlled, and the mobile terminal is able to be chargedin a fast, safe, and simply way. Furthermore, when the mobile terminalis not configured to be the mobile terminal as provided by the presentdisclosure, or the USB charger is not configured to be the USB chargeras provided by the present disclosure, the mobile terminal will becharged in a regular way. Thus, the charging method provided by thepresent disclosure has good compatibility.

Although the present disclosure has been disclosed above with referenceto preferred embodiments thereof, it should be understood by thoseskilled in the art that various changes may be made without departingfrom the spirit or scope of the disclosure. Accordingly, the presentdisclosure is not limited to the embodiments disclosed.

What is claimed is:
 1. A USB charger adapted to charge a mobileterminal, comprising a first logic control unit through whichbidirectional communication is established between the USB charger andthe mobile terminal, wherein the first logic control unit is configuredto: send, to the mobile terminal, a first signal which comprises amaximum output capability of the USB charger; receive, from the mobileterminal, a second signal which indicates magnitude of a voltagerequested by the mobile terminal; and adjust a voltage output from theUSB charger to be consistent with the voltage requested by the mobileterminal.
 2. The USB charger according to claim 1, wherein the voltagerequested by the mobile terminal is determined based on the maximumoutput capability of the USB charger and a maximum load capability ofthe mobile terminal.
 3. The USB charger according to claim 1, whereinthe bidirectional communication is established through one signal wireof an interface of the USB charger.
 4. The USB charger according toclaim 3, wherein the signal wire comprises a data signal wire D+, a datasignal wire D−, or an ID signal wire.
 5. The USB charger according toclaim 1, wherein the first signal and the second signal are pulsesignals.
 6. The USB charger according to claim 1, wherein the firstlogic control unit comprises: a first logic control circuit, a firstswitch transistor, and a first comparator, wherein the first logiccontrol circuit is configured to: send the first signal to the mobileterminal through the first switch transistor, and receive and parse thesecond signal from the mobile terminal.
 7. A mobile terminal adapted tobe charged by the USB charger according to claim 1, comprising a secondlogic control unit through which bidirectional communication isestablished between the mobile terminal and USB charger, wherein thesecond logic control unit is configured to: receive, from the USBcharger, a first signal which comprises a maximum output capability ofthe USB charger; send, to the USB charger, a second signal whichindicates magnitude of a voltage requested by the mobile terminal; andadjust a charging setting, when a voltage output from the USB charger isconsistent with the voltage requested by the mobile terminal.
 8. Themobile terminal according to claim 7, wherein the voltage requested bythe mobile terminal is determined based on the maximum output capabilityof the USB charger and a maximum load capability of the mobile terminal.9. The mobile terminal according to claim 7, wherein the bidirectionalcommunication is established through one signal wire of a USB interfaceof the mobile terminal.
 10. The mobile terminal according to claim 9,wherein the one signal wire comprises a data signal wire D+, a datasignal wire D−, or an ID signal wire.
 11. The mobile terminal accordingto claim 7, wherein the first signal and the second signal are pulsesignals.
 12. The mobile terminal according to claim 7, wherein thesecond logic control unit comprises: a second logic control circuit, asecond switch transistor, and a second comparator, wherein the secondlogic control circuit is configured to: send the second signal to theUSB charger through the second switch transistor, and receive the firstsignal from the USB charger thorough the second comparator.
 13. A methodof charging a mobile terminal according to claim 7, comprising: sendinga handshake request signal to a USB charger; receiving, from the USBcharger, a first signal which comprises a maximum output capability ofthe USB charger; sending, to the USB charger, a second signal whichindicates magnitude of a voltage requested by the mobile terminal; andadjusting a charging setting of the mobile terminal when a voltageoutput from the USB charger is consistent with the voltage requested bythe mobile terminal.
 14. The method according to claim 13, furthercomprising detecting a type of the USB charger.
 15. The method accordingto claim 13, further comprising: detecting a charging state of themobile terminal; and adjusting a charging current when the chargingstate is detected abnormal.
 16. The method according to claim 13,wherein the first signal, the second signal and the handshake requestsignal are pulse signals.
 17. The method according to claim 13, furthercomprising: charging the mobile terminal with a regular voltage, whenthe first signal is not received from the USB charger.
 18. A method ofcharging a mobile terminal by a USB charger according to claim 1,comprising: receiving a handshake request signal from the mobileterminal; sending, to the mobile terminal, a first signal whichcomprises a maximum output capability of the USB charger; receiving,from the mobile terminal, a second signal which indicates magnitude of avoltage requested by the mobile terminal; and adjusting a voltage outputfrom the USB charger to be consistent with the voltage requested by themobile terminal.
 19. The method according to claim 18, furthercomprising: charging the mobile terminal with a regular voltage, whenthe handshake request signal received is unable to be parsed by the USBcharger.
 20. The method according to claim 18, further comprising:charging the mobile terminal with a regular voltage, when the USBcharger is disconnected with the mobile terminal.
 21. The methodaccording to claim 18, wherein the first signal, the second signal andthe handshake request signal are pulse signals.